HELP! Balancing perfect for a week, then connected to orion DC to DC 24/12 converter and in one night 30% and 0% soc in the morning.

[robert_melton88]

First DIY RV Victron system. After finishing install and setting parameters, I allowed the system to run for over a week before finishing up by connecting a Orion 24v-12v converter to my factory lead acid batteries (two wired in parallel). System worked perfectly, with 0%-.10% deviation between the two 12v280ah SOK batteries wired in series, as read by the Victron smart shunt. Only issue i had was the smart shunt SOC would deviate from blthe batteries SOC from the BMS, even after 100% twice, the two reading (shunt vs BMS) would not remain the same at all. Smart shunt would show much lower the more discharge... but that's not my #1 issue right now (help with that would also be appreciated)
I decided to finish the system by wiring the Orion 24/12 converter to my factory lead acid batteries per diagram from Explorist life solar. There are two 12v batteries in parallel that were in need of a charge. Off the converter, I wired positive to positive terminal of bat #1 and negative to Negative terminal of bat #2. Everything was fine after a several hrs so I called it a night. When I woke up, the Multiplus was off (low battery). After checking the Shunt readout it alerted low battery voltage and 111% deviation. SOK BMS confirmed with one battery at 30% and one at zero. I'll try to attach the diagram I got. The only two differences is I didn't use Orion chargers for alternators and I have 150a DC breaker after the Orion leading to the lead acid 12v's. Also there are two 12v lead acid batteries. Not sure if that matters. Any help would be greatly appreciated. Currently re-balancing the lifepo4 batteries now with Orion disconnect.

 

[robert_melton88]

Also, the factory 12v Lead acid batteries Negative goes to chassis ground vs back to main panel (diagram above shows pos and negative back to panel) whereas the factory wiring has a positive from batteries to panel, and negative to ground. Since this was working fine I didn't run a negative to anywhere else.

 

[HRTKD]

I wouldn't use a converter to charge batteries. That's not say that you can't. Lead acid as the target isn't as bad, but I would still want to see a charger there, not a converter. Hang an Orion XS off of the converter to charge the batteries.

If there wasn't an active charge source then the converter shouldn't have been on. Then again, it shouldn't have drained the LiFePO4 battery bank overnight unless your lead acid battery bank was severely depleted. I wouldn't have connected the converter with a depleted target battery bank.

I don't know what the converter you're using has for low voltage limits. They may be too low for a LiFePO4 source.

 

[HarryN]

Step 1 is to wire your sok batteries in parallel, and charge / discharge them a few times together so that they are balanced.

My guess is that you have not fully charged them based on what you report so far.

____________

( 2 batteries ) x ( ~ 200 amp-hrs ) x ( 12 volt ) ~ 4 kW-hrs if completely full.

_______________

Inverter standby ( 50 watts ) x ( 12 hours ) ~ 600 watt-hrs overnight.

You didn't say how large your AGM battery pack is, but let's assume

( 300 amp-hrs ) x ( 12 volt ) ~ 3.5 kW-hrs plus some overhead

So it all makes sense on paper.

 

[robert_melton88]

Step 1 is to wire your sok batteries in parallel, and charge / discharge them a few times together so that they are balanced.

My guess is that you have not fully charged them based on what you report so far.

____________

( 2 batteries ) x ( ~ 200 amp-hrs ) x ( 12 volt ) ~ 4 kW-hrs if completely full.

_______________

Inverter standby ( 50 watts ) x ( 12 hours ) ~ 600 watt-hrs overnight.

You didn't say how large your AGM battery pack is, but let's assume

( 300 amp-hrs ) x ( 12 volt ) ~ 3.5 kW-hrs plus some overhead

So it all makes sense on paper.

Only issue I have is using the power after charging in parallel... the inverter is 24v. I suppose I could hook it up to the 12v system and run the lights / fridge DC. Any suggestions? With the weather right now, it's time consuming to charge, let alone discharge @12v without the inverter on. Also I didn't discharge the batteries as you suggested, however I did charge them full, checked voltage with meter and linked in parallel for 2 days to balance initially.

 

[HarryN]

Only issue I have is using the power after charging in parallel... the inverter is 24v. I suppose I could hook it up to the 12v system and run the lights / fridge DC. Any suggestions? With the weather right now, it's time consuming to charge, let alone discharge @12v without the inverter on. Also I didn't discharge the batteries as you suggested, however I did charge them full, checked voltage with meter and linked in parallel for 2 days to balance initially.

After the batteries are balanced from being in parallel, then go ahead and wire them in series again to get 24 volt.

The resting voltage should be not more than 0.1 volts different between them.

Your are right - it takes a long time to discharge anything using most DC stuff. Just bring it down "some".

I suppose you could just wire them in series and discharge through the inverter as well - just use a blow dryer or something like that.

 

[robert_melton88]

After the batteries are balanced from being in parallel, then go ahead and wire them in series again to get 24 volt.

The resting voltage should be not more than 0.1 volts different between them.

Your are right - it takes a long time to discharge anything using most DC stuff. Just bring it down "some".

I suppose you could just wire them in series and discharge through the inverter as well - just use a blow dryer or something like that.

I appreciate the info, I will, like you said, series the batteries after charged full within .10 and use the inverter. Kinda a pain because of where I put the batteries. I have to pull the component board and open like a door to get to them... and it's a bit of a reach.. but i can do that. The hardest part to get through my Carpenter head of this install is the settings for the system.. All SOK said was just double the numbers from 12v.. but I'm uneasy since I'm a noob... I think I have everything right since the system worked great for a couple weeks.. this damn 24-12v charge/ conversion took my confidence away.

 

[HarryN]

I appreciate the info, I will, like you said, series the batteries after charged full within .10 and use the inverter. Kinda a pain because of where I put the batteries. I have to pull the component board and open like a door to get to them... and it's a bit of a reach.. but i can do that. The hardest part to get through my Carpenter head of this install is the settings for the system.. All SOK said was just double the numbers from 12v.. but I'm uneasy since I'm a noob... I think I have everything right since the system worked great for a couple weeks.. this damn 24-12v charge/ conversion took my confidence away.

You are doing fine. 24 volt is the right decision. I am in the bay area east bay if that is at all helpful.

 

[mikefitz]

two 12v280ah SOK batteries wired in series,

You problem is using two 12v lithium batteries in series, nothing to do with the 12 to 24 converter.
Charge seperatly each of the 12v SOK batteries to 13.8 volts and hold that voltage for several hours, this will give time for the cells to balance.
Connect in series and add a battery balancer/ equiliser to your circuit.

Battery Balancer | Victron Energy

Equalize the state of charge of two series connected 12V batteries using the Battery Balancer. Find a Victron Energy dealer near you.

www.victronenergy.com

When charging the series 24 volt battery bank use a conservative charge voltage, 28.4 v absorbtion, 13.5v float . If you experience either of the SOK batteries entering protection, rebalance each as a 12v battery or lower the 24 volt absorbtion voltage.

With the smart shunt ensure nothing is connected to the negative of the 24v pack other than the shunt battery connection. Set up the smart shunt, 'full voltage' to 0.2 volts lower than the absorbtion voltage.